JPH042191B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a contact heat fixing device for an electrophotographic copying machine or a printing machine.

[Conventional technology]

Conventional fixing devices include beam heating using infrared rays, hot plate heating, ribbon heater heating, and heated roller fixing using rolls, but these devices have good thermal efficiency, have little risk of ignition, and are smaller. 2. Description of the Related Art Heat roller fixing devices, which have the advantage of being easy to configure, are often used in electrophotographic copying machines and the like. The heat roller fixing device is divided into a fixing roller that heats and fixes the recorded image surface of the recording paper, and a pressure roller that presses the non-image surface of the recording paper, and applies a constant pressure between the two rollers and rotates them while heating. A recording paper having an unfixed toner image is passed between the rollers to fix the toner image on the recording paper.

Conventional fusing rollers have heat-resistant,
A coating coated with a tetrafluoroethylene resin (hereinafter referred to as Teflon registered trademark resin) with excellent mold release properties is used, and a silicone rubber roller with elasticity and excellent heat resistance is used as the pressure roller. In order to efficiently fix a recorded image, it is best to fix it by applying heat and pressure, and although it varies depending on the fixing speed and type of toner, generally the surface temperature of the fixing roller is 150 to 240.
℃, the average temperature is 180℃, and the pressure of the pressure roller is 20~
It is used with a weight of 50kg. In this case, it is known from experience that if the pressure of the pressure roller is reduced, the surface temperature of the fixing roller must be set high. There is a pressure roller that uses an RTV silicone rubber roller containing silicone oil, but the offset prevention performance of this roller deteriorates over time, and an offset phenomenon gradually occurs during long-term use, and eventually In this case, a large amount of offset toner accumulates on the roller section, making it impossible to obtain normal copies.

As a countermeasure to this problem, a perfluoroalkoxytetrafluoroethylene resin tube (which has excellent non-adhesive properties and can be used stably up to temperatures around 250°C) has been added to the silicone rubber roller. A coated tube with the structural formula of It has been pointed out that there is a drawback in that the recording paper is likely to become electrified even when it is twisted, and the recording paper is likely to be wrapped around it due to the electrification. In addition, the PFA tube coating increases the surface hardness of the pressure roller, which tends to cause slight slippage between the fixing roller and the pressure roller during the fixing operation. Scratches occur on the roller surface, which promotes toner adsorption to the roller surface, causing stains and also contributing to the occurrence of wrinkles on the recording paper.

[Problem that the invention seeks to solve]

The present invention provides a fixing device equipped with a fixing roller and a pressure roller that presses against the fixing roller.
Good fixation is achieved regardless of the thickness of the recording paper, such as thick recording paper, and the toner adheres to the pressure roller surface.
It is an object of the present invention to provide a fixing device that automatically wipes away paper dust and the like and provides stable and efficient fixing performance over a long period of time.

[Means for solving problems]

The present invention aims to achieve the above object, and a recording paper guide section for placing and guiding the recording paper carrying an unfixed toner image thereon has a flexible elastic member on the downstream side of the entrance guide plate. The fixing device is provided with a guide plate, and the fixing unit includes a fixing roller that fixes the recording paper on which the unfixed toner is placed, and a pressure roller that can be pressed against and separated from the fixing roller, the fixing device including the elastic guide. During fusing, the plate brings the leading edge of the recording paper into contact with the circumferential surface of the fixing roller in the case of thin recording paper and guides it to the nip, while in the case of thick recording paper, the leading edge of the recording paper goes directly to the nip. This is an elastic guide plate oriented toward the fixing roller that elastically deforms due to the weight of the recording paper as it passes through the recording paper, and the pressure roller is a silicone rubber roller coated with a perfluoroalkoxytetrafluoroethylene resin tube (PFA tube). , a coating means for applying silicone oil to the pressure roller and a cleaning blade for cleaning the pressure roller are disposed on the upstream side and the cleaning blade on the downstream side when viewed from the rotation direction of the pressure roller, an elastic member that rotates the cleaning blade with a fulcrum on the circumferential surface of the pressure roller and slides it into sliding contact with the circumferential surface of the pressure roller; and when the pressure roller is separated from the fixing roller, the cleaning blade rotates to follow the movement of the pressure roller. a regulating member that stops the moving application means and the cleaning blade in the middle of rotation;
The present invention provides a fixing device characterized in that it is provided with.

That is, the present invention prevents dirt on the pressure roller.
For example, you can coat a silicone rubber roller with a PFA tube, clean the roller with a cleaning blade, and apply a release oil such as silicone oil to prevent the pressure roller from slipping with the fixing roller due to an increase in the hardness of the pressure roller due to the PFA tube coating. The present invention provides a fixing device in which a pressure roller is coated with the coating, and the fixing roller is prevented from being scratched even if slippage occurs between the two rollers.

〔Example〕

The figure is a side sectional view for explaining an embodiment of the heat fixing device of the present invention. In the figure, reference numeral 1 indicates a fixing roller, and a metal cylinder 2 made of aluminum, stainless steel, etc. is thinly coated with, for example, Teflon registered trademark resin 3, which has a smooth surface and has good releasability from toner, to prevent offset. is rotatably supported. An infrared lamp 4 is built in the hollow interior of the fixing roller 1 as a heating element. Further, a soft cleaning roller 5 that rotates following the rotation of the fixing roller 1 is provided on one side of the fixing roller 1 so as to be in contact with the surface. The cleaning roller 5
It is preferable that the material has higher surface energy than the fixing roller 1, such as a foamed silicone rubber roller.

The pressure roller 6 has a hollow cylinder 7 made of metal such as aluminum or stainless steel as its core, on which a relatively thick HTV silicone rubber layer 8 is formed, and a PFA tube 9 with good releasability from toner on the surface.
During the fixing operation, the fixing roller 1 comes into contact with the fixing roller 1 with a required pressure and rotates as the fixing roller rotates. During a non-fixing operation, a mechanism (not shown) on the main body side of the apparatus releases the pressure contact with the fixing roller 1 and positions it at the dotted line 6' position. On one side of the pressure roller 6, an application member for applying releasable silicone oil and a cleaning member for cleaning paper powder and foreign matter are provided. To explain these in detail, 10 is a silicone oil-impregnated felt, which is detachably attached to one end of the arm 11, and the other end of the arm 11 is fitted to a pin 12 that is the center of swing of the arm 11. There is. Due to the bias of the spring 13, the impregnated felt 10 slides into contact with the circumferential surface of the pressure roller 6 with an appropriate pressure, thereby forming a thin coating of silicone oil on the surface of the pressure roller 6. On the other hand, in the cleaning member for removing paper dust and foreign matter, a cleaning blade 14 made of polyurethane resin is fixed to one end of an arm 15, and the other end of the arm 15 is fitted into a pin 16 that is the center of swing of the arm 15. It is worn. Spring 1
The cleaning blade 14 rotates about the pin 16 as a fulcrum so that the cleaning blade 14 slides into contact with the pressure roller 6 and maintains a pressure and angle that makes it easy to clean paper powder and foreign matter adhering to the pressure roller 6. The shapes and tensions of the arm 15 and spring 17 are set. The stopper members 18 and 19 are provided on the apparatus main body side, respectively, and are used to restrict rotation of the applicator member and the cleaning member in the counterclockwise direction beyond a certain level. That is, during a non-fixing operation, the pressure roller 6 is released from pressure contact with the fixing roller 1 by a mechanism not shown, and is positioned at the position indicated by the dotted line 6' in the figure. In this case, the stopper member 18,
Reference numeral 19 is for configuring the silicone oil-impregnated felt 10 and the cleaning blade 14 to be spaced apart from the circumferential surface of the pressure roller 6.

Next, the operation of the present invention will be explained. On the right side of the fixing device in the figure, an upper entrance guide plate 20 and a lower entrance guide plate 21 made of metal or resin are provided as transport guide plates for guiding the recording paper P carrying the unfixed toner image T to the fixing section. ing. On the downstream side of the lower entrance guide plate, a flexible elastic guide member 22, such as a Mylar base, is provided as shown. The elastic guide member 22 is used to prevent wrinkles from forming when fixing the recording paper P. In the case of thin recording paper, the leading edge of the recording paper is brought into contact with the circumferential surface of the fixing roller 1 before being nipped. In the case of thick recording paper, this is to direct the leading edge of the recording paper directly toward the nip portion. Reference numeral 23 denotes a regulating member attached to the main body of the apparatus, which regulates the guide member 22 from being biased downward from this part. In this embodiment, the elastic guide member 22 is provided, but the same effect can be obtained even if the lower entrance guide plate 21 is made of a suitable elastic member. The fixing roller 1 and the pressure roller 6 are rotated in the direction of the arrow shown while maintaining a required pressure by a main body drive mechanism (not shown), and after fixing the toner image T on the recording paper P, the recording paper P is conveyed to the left side in the drawing. The separation claws 24 and 25 are provided so as to lightly contact the circumferential surfaces of the fixing roller 1 and the pressure roller 6, respectively, to prevent the recording paper P from being wrapped around the roller portions.

As mentioned above, the fixing roller 1 is coated with Teflon resin with a smooth surface, and the pressure roller 6 is coated with silicone rubber 8 and a PFA tube 9 with a smooth surface and good releasability for toner. The surface hardness of No. 6 becomes higher. According to the inventor's experiments, the surface hardness of HTV silicone rubber with a wall thickness of approximately 5 mm is approximately 25 degrees, and when the roller is coated with a PFA tube with a thickness of approximately 0.5 mm, the surface hardness of the roller becomes approximately 80 degrees. . When the roller is brought into pressure contact with the fixing roller 1 and rotated, slippage occurs between the two rollers, scratches occur on the surface of the fixing roller 1, the smoothness is lost, and toner or foreign matter tends to adhere to the surface of the fixing roller 1. In addition, frictional electrification occurs due to slippage, and paper dust and the like adhere to the roller, causing poor fixing. The present inventor brought a silicone oil-impregnated felt 10 into sliding contact with the pressure roller 6, formed a silicone oil film on the surface layer of the roller, and acted as a lubricant when the two rollers slid, thereby preventing scratches on the fixing roller 1. In addition, paper dust and foreign matter adhering to the roller are removed by the cleaning blade 14, thereby solving the problem of poor fixing. Furthermore, since the silicone oil as the lubricant transfers little by little to the surface layer of the fixing roller 1, it also prevents the fixing roller 1 from becoming dirty. Note that when the application member and the cleaning member are biased clockwise against the springs 13 and 17, a locking member is provided on the device main body side (not shown), and the coating member and the cleaning member are locked at a position away from the circumferential surface of the pressure roller 6. It can be stopped. In this state, the silicone oil-impregnated felt or cleaning blade can be replaced and cleaned.

〔Effect of the invention〕

According to the present invention, even if the paper thickness of the recording paper is different,
The recording paper is guided and fixed to the fixing section without any fixing wrinkles, and the fixing section also uses a pressure roller covered with a PFA tube, an application member that applies silicone oil, and a cleaning blade that uses an elastic member to apply the silicone oil and perform the cleaning action. By making sliding contact with an appropriate pressure to achieve optimum results, the application member forms a silicone oil film on the surface layer of the pressure roller, and even if slippage occurs between the fixing roller and the pressure roller, the coating will remain intact. The fixing roller acts as a lubricant between both rollers to prevent scratches on the fixing roller, and the cleaning blade of the cleaning member can reliably clean paper dust and foreign matter. Therefore, the fixing roller and pressure roller according to the present invention can be used for a long period of time. When the fixing device of the present invention is used, it is possible to obtain a cleanly fixed copy without any stains. Particularly when double-sided copying is performed, clean copies are always obtained without toner staining on the pressure roller. Furthermore, in the present invention, when the fixing device is not in use, the pressure roller not only releases the pressure contact with the fixing roller and separates them, but also separates the application member and the cleaning blade from the pressure roller, so that when the fixing device is not in use, the pressure roller is separated from the pressure roller. The application member and cleaning blade do not come into pressure contact with a part of the roller. Therefore, not only can it be used for a longer period of time, but it also has the effect of facilitating replacement and cleaning of the fixing roller, pressure roller, coating member, cleaning blade, and the like.

[Brief explanation of drawings]

The figure is a side view for explaining one embodiment of a heat fixing device. 1... Fixing roller, 3... Tetrafluoroethylene resin, 4... Infrared lamp, 5... Cleaning roller, 6... Pressure roller, 8... HTV silicone rubber layer, 9... PFA tube, 10... Silicone oil impregnated felt, 11... Arm , 13...Spring, 1
4...Cleaning blade, 15...Arm, 17
...Spring, 18, 19...Stopper member, 20...Upper entrance guide plate, 21...Lower entrance guide plate, 22...Elastic guide member, P...Recording paper, T...Toner image.

Claims (1)

[Scope of Claims] 1. A flexible elastic guide plate is provided on the downstream side of the entrance guide plate in the recording paper guide section for placing and guiding the recording paper on which the unfixed toner image is placed, and the fixing section The fixing device includes a fixing roller that fixes the recording paper on which the unfixed toner is placed, and a pressure roller that can be brought into contact with and separated from the fixing roller, and the elastic guide plate is used to fix a thin recording sheet during fixing. In the case of paper, the leading edge of the recording paper is brought into contact with the circumferential surface of the fixing roller and then guided to the nip, and in the case of thick recording paper, the leading edge of the recording paper is guided directly to the nip as it passes through. an elastic guide plate oriented toward the fixing roller that elastically deforms due to weight, the pressure roller being a silicone rubber roller coated with a perfluoroalkoxytetrafluoroethylene resin tube (PFA tube); and a cleaning blade for cleaning the pressure roller, the coating means being disposed on the upstream side and the cleaning blade being disposed on the downstream side when viewed from the rotation direction of the pressure roller, and the coating means and the cleaning blade are disposed on the upstream side and the cleaning blade on the downstream side, respectively. an elastic member that rotates with a fulcrum on the circumferential surface of the pressure roller and slides thereon; and the application means that rotates to follow the movement of the pressure roller when the pressure roller is separated from the fixing roller. and a regulating member that stops the cleaning blade in the middle of its rotation.